Biochemical Methane Potential of the Liquid Phase from Hydrothermal Carbonization of Municipal Solid Waste
Kameron Adams, Old Dominion University-Department of Civil and Environmental Engineering
Hydrothermal carbonization (HTC) is observed as a scalable technique to convert wet biomass or organic waste (e.g. food waste and MSW) to carbon-rich solid fuels. Literature reports operating conditions of HTC ranging from 180-300°C based on different feedstocks which produces three main products; hydrochar green coal (75-80%), liquid phase with total organic carbon (TOC) (15-20%) and gases which is mainly CO2 (5%). The liquid phase of HTC contains high loads of organics and inorganics and without recovery would be lost and still be considered a waste product which could increase the load at wastewater treatment facilities; also a loss of organic carbon, which could have been used for energy applications. In this study, the liquid phase from HTC of MSW was used as the feedstock for biological treatment to evaluate biodegradability and biogas yields. A mixture of known composition (paper, plastic, metal, glass, food) representing waste that typically goes to the landfill has been created for testing under the proposed process. The purpose of this particular study was to 1) investigate carbonization experiments at varying temperatures (250, 280, 310 °C) and times (10 min, 1 h, 6 h) 2) evaluate liquid phase and biochar properties 3) preform AD bench scale bottle test on liquid phase to generate experimental data on biogas yields to understand biodegradability. Mass balance shows that 22-48% of carbon remained in the solid phase, 33-45% in the liquid phase and 15-44% in the gas phase. The condition of 280°C at 10 minutes yielded the highest TOC of 8.0 g/L with biogas yields of 222 g biogas/g TOC.
Kameron Adams is PhD Candidate in Environmental Engineering at Old Dominion University (Norfolk, Virginia). She received her M.S in Geography and Environmental Engineering at The Johns Hopkins University, and received her B.S in Chemistry and B.S in Environmental Science and Policy from the College of William and Mary. Her undergraduate research focused on quantifying mercury in catfish found in various rivers in the Chesapeake Bay in collaboration with the Virginia Institute for Marine Science (VIMS). At Johns Hopkins she worked on the Sustainable Algal Biofuels Solution: Sourcing and Recycling Nutrients from Waste Treatment Processing project. This research focused on the promise and benefits of growing algae in wastewater. Her master’s thesis focused on the pre-treatment of Nannochloropsis salina algae in order to increase methane and biogas production during anaerobic digestion. While in Baltimore, she interned with the Maryland Department of the Environment in which she collaborated with the Land Management Administration and designed a research project comparing environmental impacts of adopting various newer technologies for waste disposal in Maryland, in order to help reach their “zero waste” goals. As her passion for renewable energy continues, she is now working with her advisor Dr. Sandeep Kumar on integrated processing of municipal solid waste for maximizing carbon recovery and fuel production combining hydrothermal carbonization with anaerobic digestion of the HTC liquid phase.